Many improvements have conventionally been made to wood-type golf club heads, and particularly in the case of drivers, various proposals have been made for extending the flight-distance. For example, as shown in JP 2005-6698A, some golf club heads employ a face portion having a so-called cup face structure. Specifically, the head is constituted by a head body having an opening formed therein and a face member that covers the opening of the head body, and the face member is formed in the shape of a cup having a plate-shaped face portion and a peripheral portion that extends from the peripheral edge of the face portion. Providing such a peripheral portion on the face member increases the amount of flexure of the face member when hitting a ball, thus obtaining effects of improving the restitution performance and extending the flight-distance.
In particular, in the golf club head disclosed in JP 2005-6698A, the restitution performance is improved by adjusting the wall thickness of the crown portion. Specifically, the wall thickness of the crown portion of the head body is set lower than the wall thickness of the opposing peripheral portion of the face member. Also, in the peripheral portion of the face member, the portion that opposes the crown portion of the head body has a shorter length of protrusion from the base portion of the peripheral portion in the central portion in the toe-heel direction, whereas the portions on the two sides thereof, namely the toe side and the heel side, have longer protruding lengths. In other words, a recessed portion is formed in the vicinity of the center of the peripheral portion. A protruding portion is correspondingly formed in the vicinity of the center of the crown portion, and fits into the recessed portion of the peripheral portion in the opening of the head body. Accordingly, the area of the portion with a low wall thickness increases in the vicinity of the center of the crown portion, and the restitution performance improves. On the other hand, the area of the portion with a high wall thickness increases on the toe side and the heel side of the crown portion in accordance with the peripheral portion, and therefore durability improves.